Solve for X.

log(x^2-9)-1=log(x+3)

log(x^2-9) - log 10 = log(x+3)

so,
(x^2-9)/10 = x+3
x^2 - 9 = 10x + 30
x^2 - 10x - 39 = 0
(x-13)(x+3) = 0
x = 13 or -3

However if x is -3, x^2-9 and x+3 = 0, so the log is not defined.

So, the only solution is x=13